require 'Win32API'
module Win32

=begin rdoc
= Win32 Registry

win32/registry is registry accessor library for Win32 platform.
It uses dl/import to call Win32 Registry APIs.

== example
  Win32::Registry::HKEY_CURRENT_USER.open('SOFTWARE\foo') do |reg|
    value = reg['foo']                               # read a value
    value = reg['foo', Win32::Registry::REG_SZ]      # read a value with type
    type, value = reg.read('foo')                    # read a value
    reg['foo'] = 'bar'                               # write a value
    reg['foo', Win32::Registry::REG_SZ] = 'bar'      # write a value with type
    reg.write('foo', Win32::Registry::REG_SZ, 'bar') # write a value

    reg.each_value { |name, type, data| ... }        # Enumerate values
    reg.each_key { |key, wtime| ... }                # Enumerate subkeys

    reg.delete_value(name)                         # Delete a value
    reg.delete_key(name)                           # Delete a subkey
    reg.delete_key(name, true)                     # Delete a subkey recursively
  end

= Reference

== Win32::Registry class

--- info

--- num_keys

--- max_key_length

--- num_values

--- max_value_name_length

--- max_value_length

--- descriptor_length

--- wtime
    Returns an item of key information.

=== constants
--- HKEY_CLASSES_ROOT

--- HKEY_CURRENT_USER

--- HKEY_LOCAL_MACHINE

--- HKEY_PERFORMANCE_DATA

--- HKEY_CURRENT_CONFIG

--- HKEY_DYN_DATA

    Win32::Registry object whose key is predefined key.
For detail, see the MSDN[http://msdn.microsoft.com/library/en-us/sysinfo/base/predefined_keys.asp] article.

=end rdoc

  class Registry

    #
    # For detail, see the MSDN[http://msdn.microsoft.com/library/en-us/sysinfo/base/registry.asp].
    #
    # --- HKEY_*
    #
    #     Predefined key ((*handle*)).
    #     These are Integer, not Win32::Registry.
    #
    # --- REG_*
    #
    #     Registry value type.
    #
    # --- KEY_*
    #
    #     Security access mask.
    #
    # --- KEY_OPTIONS_*
    #
    #     Key options.
    #
    # --- REG_CREATED_NEW_KEY
    #
    # --- REG_OPENED_EXISTING_KEY
    #
    #     If the key is created newly or opened existing key.
    #     See also Registry#disposition method.
    module Constants
      HKEY_CLASSES_ROOT = 0x80000000
      HKEY_CURRENT_USER = 0x80000001
      HKEY_LOCAL_MACHINE = 0x80000002
      HKEY_USERS = 0x80000003
      HKEY_PERFORMANCE_DATA = 0x80000004
      HKEY_PERFORMANCE_TEXT = 0x80000050
      HKEY_PERFORMANCE_NLSTEXT = 0x80000060
      HKEY_CURRENT_CONFIG = 0x80000005
      HKEY_DYN_DATA = 0x80000006

      REG_NONE = 0
      REG_SZ = 1
      REG_EXPAND_SZ = 2
      REG_BINARY = 3
      REG_DWORD = 4
      REG_DWORD_LITTLE_ENDIAN = 4
      REG_DWORD_BIG_ENDIAN = 5
      REG_LINK = 6
      REG_MULTI_SZ = 7
      REG_RESOURCE_LIST = 8
      REG_FULL_RESOURCE_DESCRIPTOR = 9
      REG_RESOURCE_REQUIREMENTS_LIST = 10
      REG_QWORD = 11
      REG_QWORD_LITTLE_ENDIAN = 11

      STANDARD_RIGHTS_READ = 0x00020000
      STANDARD_RIGHTS_WRITE = 0x00020000
      KEY_QUERY_VALUE = 0x0001
      KEY_SET_VALUE = 0x0002
      KEY_CREATE_SUB_KEY = 0x0004
      KEY_ENUMERATE_SUB_KEYS = 0x0008
      KEY_NOTIFY = 0x0010
      KEY_CREATE_LINK = 0x0020
      KEY_READ = STANDARD_RIGHTS_READ |
        KEY_QUERY_VALUE | KEY_ENUMERATE_SUB_KEYS | KEY_NOTIFY
      KEY_WRITE = STANDARD_RIGHTS_WRITE |
        KEY_SET_VALUE | KEY_CREATE_SUB_KEY
      KEY_EXECUTE = KEY_READ
      KEY_ALL_ACCESS = KEY_READ | KEY_WRITE | KEY_CREATE_LINK

      REG_OPTION_RESERVED = 0x0000
      REG_OPTION_NON_VOLATILE = 0x0000
      REG_OPTION_VOLATILE = 0x0001
      REG_OPTION_CREATE_LINK = 0x0002
      REG_OPTION_BACKUP_RESTORE = 0x0004
      REG_OPTION_OPEN_LINK = 0x0008
      REG_LEGAL_OPTION = REG_OPTION_RESERVED |
        REG_OPTION_NON_VOLATILE | REG_OPTION_CREATE_LINK |
        REG_OPTION_BACKUP_RESTORE | REG_OPTION_OPEN_LINK

      REG_CREATED_NEW_KEY = 1
      REG_OPENED_EXISTING_KEY = 2

      REG_WHOLE_HIVE_VOLATILE = 0x0001
      REG_REFRESH_HIVE = 0x0002
      REG_NO_LAZY_FLUSH = 0x0004
      REG_FORCE_RESTORE = 0x0008

      MAX_KEY_LENGTH = 514
      MAX_VALUE_LENGTH = 32768
    end
    include Constants
    include Enumerable

    #
    # Error
    #
    class Error < ::StandardError
      FormatMessageA = Win32API.new('kernel32.dll', 'FormatMessageA', 'LPLLPLP', 'L')
      def initialize(code)
        @code = code
        msg = "\0".force_encoding(Encoding::ASCII_8BIT) * 1024
        len = FormatMessageA.call(0x1200, 0, code, 0, msg, 1024, 0)
        msg = msg[0, len].force_encoding(Encoding.find(Encoding.locale_charmap))
        super msg.tr("\r", '').chomp
      end
      attr_reader :code
    end

    #
    # Predefined Keys
    #
    class PredefinedKey < Registry
      def initialize(hkey, keyname)
        @hkey = hkey
        @parent = nil
        @keyname = keyname
        @disposition = REG_OPENED_EXISTING_KEY
      end

      # Predefined keys cannot be closed
      def close
        raise Error.new(5) ## ERROR_ACCESS_DENIED
      end

      # Fake #class method for Registry#open, Registry#create
      def class
        Registry
      end

      # Make all
      Constants.constants.grep(/^HKEY_/) do |c|
        Registry.const_set c, new(Constants.const_get(c), c)
      end
    end

    #
    # Win32 APIs
    #
    module API
      [
        %w/RegOpenKeyExA    LPLLP        L/,
        %w/RegCreateKeyExA  LPLLLLPPP    L/,
        %w/RegEnumValueA    LLPPPPPP     L/,
        %w/RegEnumKeyExA    LLPPLLLP     L/,
        %w/RegQueryValueExA LPLPPP       L/,
        %w/RegSetValueExA   LPLLPL       L/,
        %w/RegDeleteValue   LP           L/,
        %w/RegDeleteKey     LP           L/,
        %w/RegFlushKey      L            L/,
        %w/RegCloseKey      L            L/,
        %w/RegQueryInfoKey  LPPPPPPPPPPP L/,
      ].each do |fn|
        const_set fn[0].intern, Win32API.new('advapi32.dll', *fn)
      end

      module_function

      def check(result)
        raise Error, result, caller(2) if result != 0
      end

      def packdw(dw)
        [dw].pack('V')
      end

      def unpackdw(dw)
        dw += [0].pack('V')
        dw.unpack('V')[0]
      end

      def packqw(qw)
        [ qw & 0xFFFFFFFF, qw >> 32 ].pack('VV')
      end

      def unpackqw(qw)
        qw = qw.unpack('VV')
        (qw[1] << 32) | qw[0]
      end

      def OpenKey(hkey, name, opt, desired)
        result = packdw(0)
        check RegOpenKeyExA.call(hkey, name, opt, desired, result)
        unpackdw(result)
      end

      def CreateKey(hkey, name, opt, desired)
        result = packdw(0)
        disp = packdw(0)
        check RegCreateKeyExA.call(hkey, name, 0, 0, opt, desired,
                                   0, result, disp)
        [ unpackdw(result), unpackdw(disp) ]
      end

      def EnumValue(hkey, index)
        name = ' ' * Constants::MAX_KEY_LENGTH
        size = packdw(Constants::MAX_KEY_LENGTH)
        check RegEnumValueA.call(hkey, index, name, size, 0, 0, 0, 0)
        name[0, unpackdw(size)]
      end

      def EnumKey(hkey, index)
        name = ' ' * Constants::MAX_KEY_LENGTH
        size = packdw(Constants::MAX_KEY_LENGTH)
        wtime = ' ' * 8
        check RegEnumKeyExA.call(hkey, index, name, size, 0, 0, 0, wtime)
        [ name[0, unpackdw(size)], unpackqw(wtime) ]
      end

      def QueryValue(hkey, name)
        type = packdw(0)
        size = packdw(0)
        check RegQueryValueExA.call(hkey, name, 0, type, 0, size)
        data = ' ' * unpackdw(size)
        check RegQueryValueExA.call(hkey, name, 0, type, data, size)
        [ unpackdw(type), data[0, unpackdw(size)] ]
      end

      def SetValue(hkey, name, type, data, size)
        check RegSetValueExA.call(hkey, name, 0, type, data, size)
      end

      def DeleteValue(hkey, name)
        check RegDeleteValue.call(hkey, name)
      end

      def DeleteKey(hkey, name)
        check RegDeleteKey.call(hkey, name)
      end

      def FlushKey(hkey)
        check RegFlushKey.call(hkey)
      end

      def CloseKey(hkey)
        check RegCloseKey.call(hkey)
      end

      def QueryInfoKey(hkey)
        subkeys = packdw(0)
        maxsubkeylen = packdw(0)
        values = packdw(0)
        maxvaluenamelen = packdw(0)
        maxvaluelen = packdw(0)
        secdescs = packdw(0)
        wtime = ' ' * 8
        check RegQueryInfoKey.call(hkey, 0, 0, 0, subkeys, maxsubkeylen, 0,
          values, maxvaluenamelen, maxvaluelen, secdescs, wtime)
        [ unpackdw(subkeys), unpackdw(maxsubkeylen), unpackdw(values),
          unpackdw(maxvaluenamelen), unpackdw(maxvaluelen),
          unpackdw(secdescs), unpackqw(wtime) ]
      end
    end

    #
    # Replace %\w+% into the environment value of what is contained between the %'s
    # This method is used for REG_EXPAND_SZ.
    #
    # For detail, see expandEnvironmentStrings[http://msdn.microsoft.com/library/en-us/sysinfo/base/expandenvironmentstrings.asp] \Win32 \API.
    #
    def self.expand_environ(str)
      str.gsub(/%([^%]+)%/) { ENV[$1] || ENV[$1.upcase] || $& }
    end

    @@type2name = { }
    %w[
      REG_NONE REG_SZ REG_EXPAND_SZ REG_BINARY REG_DWORD
      REG_DWORD_BIG_ENDIAN REG_LINK REG_MULTI_SZ
      REG_RESOURCE_LIST REG_FULL_RESOURCE_DESCRIPTOR
      REG_RESOURCE_REQUIREMENTS_LIST REG_QWORD
    ].each do |type|
      @@type2name[Constants.const_get(type)] = type
    end

    #
    # Convert registry type value to readable string.
    #
    def self.type2name(type)
      @@type2name[type] || type.to_s
    end